Field emission display having gate plate

ABSTRACT

The present invention relates to a field emission display in which a gate plate having a gate hole and a gate electrode around the gate hole is formed between an anode plate having phosphor and a cathode plate having a field emitter and a control device for controlling field emission current, wherein the field emitter of the cathode plate is constructed to be opposite to the phosphor of the anode plate through the gate hole.  
     According to the present invention, it is possible to significantly reduce the display row/column driving voltage by applying scan and data signals of the field emission display to the control device of each pixel, And the present invention is directed to improve the brightness of the field emission display in such a manner that the electric field necessary for field emission is applied through the gate electrode of the gate plate to freely control the distance between the anode plate and the cathode plate, so that a high voltage can be applied to the anode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a field emission display (FED)in which the field emission device is applied to a flat display, and inparticular, to the field emission display in which a gate plate having agate hole and a gate electrode around the gate hole is formed between ananode plate having phosphor and a cathode plate having a field emitterand a control device for controlling field emission current, wherein thefield emitter of the cathode plate is constructed to be opposite to thephosphor of the anode plate through the gate hole.

[0003] 2. Background of the Related Art

[0004] A field emission display is a device representing an imagethrough cathodeluminescence of a phosphor, by colliding electron emittedfrom the field emitter of a cathode plate against the phosphor of ananode plate, wherein the cathode plate having the field emitter and theanode plate with the phosphor are formed to be opposite to each other byvacuum packaging with them separated by a given distance (for example, 2mm). Recently, many researches and developments have been made on thefield emission display as the flat display capable of replacing theconventional cathode ray tube (CRT). Electron emission efficiency in thefield emitter being a kernel constitutional element of the fieldemission display is variable depending on a device structure, an emittermaterial and a shape of the emitter.

[0005] The structure of the field emission device can be mainlyclassified into a diode type having the cathode (or emitter) and theanode, and a triode having the cathode, the gate and the anode. Metal,silicon, diamond, diamond-like carbon, carbon nanotube, and the like areusually used as the emitter material. In general, metal and silicon aremanufactured to the triode structure and diamond, carbon nanotube, etc.manufactured to the diode structure.

[0006] The diode field emitter is usually formed by making a diamond ora carbon nanotube film-shaped. The diode field emitter has advantages insimplicity of the manufacturing process and high reliability of theelectron emission, even though it has disadvantages in controllabilityof the electron emission and low-voltage driving, compared with thetriode field emitter.

[0007] Hereinafter, a conventional field emission display having fieldemitters will be described with reference to the accompanying drawings.

[0008]FIG. 1 is a perspective view schematically illustrating theconstruction of a conventional field emission display having a diodefield emitter.

[0009] A cathode plate has cathode electrodes 11 arranged in a beltshape on a lower glass substrate 10B and film-shaped field emittermaterials 12 on a portion of there. An anode plate has transparent anodeelectrodes 13 arranged in a belt shape on an upper glass substrate 10Tand phosphors 14 of red (R), green (G) and blue (B) on a portion ofthere. The cathode plate and the anode plate are vacuum packaged inparallel, while facing each other, by means of using spacers 15 as asupporter. The cathode electrodes 11 of the cathode plate and thetransparent anode electrodes 13 of the anode plate are arranged tointersect each other. In the above, an intersecting region is defined asone pixel.

[0010] In the field emission display shown in FIG. 1, the electric fieldrequired for electron emission is given by the voltage differencebetween the cathode electrodes 11 and the anode electrodes 13. It hasbeen noted that electron emission usually occurs in the field emitterwhen the electric field is applied to the field emitter material in thevalue more than 0.1 V/μm.

[0011]FIG. 2 shows the field emission display that was proposed in orderto improve the disadvantages of the field emission display shown in FIG.1, which schematically illustrates the construction of a conventionalfield emission display using a control device for controlling the fieldemitter in each pixel of the cathode plate.

[0012] The cathode plate includes a belt shaped scan signal line 21S anda data signal line 21D, which are formed of a metal on a glass substrate20B and capable of an electrical row/column addressing, a film (thinfilm or thick film) shaped field emitter 22, in which each pixel definedby the scan signal line 21S and the data signal line 21D is formed ofdiamond, diamond-like carbon, carbon nanotube, etc., and control devices23 connected to the scan signal line 21S, the data signal line 21D andthe field emitter 22 to control a field emission current depending ofthe scan and the data signals of the display. The anode plate includestransparent anode electrodes 24 arranged in a belt shape on a glasssubstrate 20T and phosphors 25 of red (R), green (G) and blue (B) on aportion of there. The cathode plate and the anode plate are vacuumpackaged in parallel, while facing each other, by means of using spacers26 as a supporter.

[0013] In the field emission display shown in FIG. 2, a high voltage isapplied to the anode electrodes 24 to induce electron emission from thefilm-shaped field emitter 22 in the cathode plate and to accelerate theemitted electrons with high energy at the same time. Then, if a signalof the display is inputted to the control devices 23 through the scansignal line 21S and the data signal line 21D, the control device 23controls the amount of electrons emitted from the film-shaped fieldemitter to represent row/column images.

[0014] The diode field emitter used for the field emission displaysshown in FIG. 1 and FIG. 2, as described above, has advantages that astructure is simple and a manufacturing process is easy, since it doesnot need a gate and a gate insulating film unlike a conic triode fieldemitter.

[0015] Further, the diode field emitter has very low probability in thebreakdown of the field emitter by the sputtering effect upon emission ofthe electrons, so that it has a high reliability and there is nobreakdown phenomenon of the gate and the gate insulator that is veryproblematic in the triode field emitter.

[0016] In the field emission display having the diode field emittershown in FIG. 1, however, a high electric field necessary for fieldemission is applied through the electrodes (cathode electrodes 11 andtransparent anode electrodes 13 in FIG. 1) of the upper and lower platesthat are separated by a significant distance (usually, 200 μm to 2 mm),so that a display signal having high voltage is required. As a result,there is a disadvantage that an expensive high voltage driving circuitis required.

[0017] In particular, in the field emission display having the diodefield emitter of FIG. 1, although the voltage necessary for electronemission is lowered by reducing the distance between the upper plate andthe lower plate, low voltage driving is nearly impossible since theanode electrode 13 is used as the acceleration electrode of the electronas well as the signal line of the display. In the field emissiondisplay, a high-energy electron over 200 eV is required to emit thephosphor. The higher electron energy is, the better luminous efficiencyis. Thus, a high-brightness field emission display can be obtained onlyif the high voltage is applied to the anode electrode.

[0018] In the conventional active-matrix field emission display havingthe diode field emitter shown in FIG. 2, the control device 23 of thefield emitter is used in each pixel and, by inputting the display signalthrough it, the active-matrix field emission display can solve the highvoltage driving problem in FIG. 1 and the problems such asnon-uniformity of electron emission, cross talk, etc. at the same time.The high voltage applied to the anode electrode 24 for the fieldemission and electron acceleration, however, comes to induce asignificant voltage to the control devices 23 of each pixel. And, if thevoltage is induced more than the breakdown voltage of the controldevices 23, the control device could be failed.

[0019] Therefore, the conventional active-matrix field emission displayhas disadvantages that the voltage that can be applied to the anodeelectrodes 24 is limited depending on the breakdown characteristics ofthe control devices 23 and it is difficult to fabricate the fieldemission display having the high brightness due to the limited anodevoltage.

SUMMARY OF THE INVENTION

[0020] Accordingly, the present invention has been made in view of theabove problems, and the present invention is directed to significantlyreduce the display row/column driving voltage by applying scan and datasignals of the field emission display to the control device of eachpixel.

[0021] And the present invention is directed to improve the brightnessof the field emission display in such a manner that the electric fieldnecessary for field emission is applied through the gate electrode ofthe gate plate to freely control the distance between the anode plateand the cathode plate, so that a high voltage can be applied to theanode.

[0022] In addition, the present invention is directed to allow the gateplate and the cathode plate to be separately fabricated and thenassembled, so that the facilitating process can be readily performed,and the productivity and yield can be improved by fundamentally removingthe breakdown of the gate insulating film of the field emitter.

[0023] To achieve the above objects, according to one aspect of thepresent invention, there is provided a field emission display having agate plate, comprising: an anode plate having a transparent electrode ona substrate and a phosphor on a portion of the transparent electrode; acathode plate having row/column signal lines of a belt shape for whichrow/column addressing is possible on the substrate, and pixels eachdefined by the row signal line and the column signal line, wherein eachpixel has a film-shaped field emitter and a control device forcontrolling the field emitter, having two terminals connected to atleast the row/column signal lines and one terminal connected to thefilm-shaped field emitter; a gate plate having gate holes penetratingtherein and a gate electrode around the top of the gate holes; andspacers for supporting the gate plate between the cathode plate and theanode plate, wherein the field emitter of the cathode plate isconstructed to be opposite to the phosphor of the anode plate throughthe gate holes and is formed by vacuum packaging.

[0024] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, theanode plate, the cathode plate and the gate plate are preferably formedof different insulating substrates.

[0025] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, thespacers are preferably formed between the cathode plate and the gateplate and between the anode plate and the gate plate.

[0026] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, thephosphor of each pixel is the phosphor of red (R), green (G) or blue(B).

[0027] In addition, in the aforementioned of a field emission displayhaving a gate plate according to another embodiment of the presentinvention, an optical-shielding film (black matrix) is further formed ata given region between the phosphors of the anode.

[0028] Preferably, the field emitter is formed of a thin film or a thickfilm comprising a diamond, a diamond carbon, or a carbon nanotube, andthe control device is a thin film transistor or ametal-oxide-semiconductor field effect transistor.

[0029] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, the gateelectrode is applied to a DC voltage to induce an electron emission fromthe film-shaped field emitter in the cathode plate; the emittedelectrons are accelerated with high energy by applying the DC voltage tothe transparent electrode of the anode plate; and scan and data signalsare addressed to the control device of the field emitter in each pixelof the cathode plate, whereby the control device of the field emittercontrols the electron emission of the field emitter to represent images.

[0030] Further, the gate electrode of the gate plate is applied to theDC voltage in the range of 50 to 1500V and the transparent electrode ofthe anode plate is applied to the DC voltage of over 2 kV and, the imagegray scale is represented by changing the pulse amplitude and/or pulsewidth (duration) of the data signal voltage applied to the field emitterthrough controlling of the control device, and the voltage of the datasignal applied to the field emitter is preferably the pulse in the rangeof 0 to 50V

[0031] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, anelectron-convergence electrode is further formed between the cathodeplate and the gate plate and, said electron-convergence electrode helpsthe electrons emitted from the field emitter to be well converged on thephosphor of the anode plate and, further to prohibit the field emissionof the field emitter by the anode voltage along with said gate electrodeof the gate plate, by applying the constant voltage to saidelectron-convergence electrode and, said electron-convergence electrodeis preferably intended to serve as an optical-shielding film.

[0032] In the aforementioned of a field emission display having a gateplate according to another embodiment of the present invention, thefield emitter includes dots divided into a plurality of regions and thegate hole of the gate plate has the number corresponding to each of thedots.

[0033] In addition, the control device is a thin film transistor, whichcomprises; a gate made of a metal on the cathode plate; a gateinsulating film formed on the cathode plate including the gate; anactive layer made of a semiconductor thin film on a portion of the gateand the gate insulating film; a source and a drain formed at both endsof the active layer; and an interlayer insulating layer having a contacthole for connecting the source and the drain to the electrode.

[0034] Further, in the field emission display as described above, anelectron-convergence electrode made of a metal is further formed on theinterlayer insulating layer and, the active layer of the thin filmtransistor consists of amorphous silicon or a polysilicon layer and,preferably, the interlayer insulating film consists of an amorphoussilicon nitride film or a silicon oxide film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other objects, features and advantages of thepresent invention will be apparent from the following detaileddescription of the preferred embodiments of the invention in conjunctionwith the accompanying drawings, in which:

[0036]FIG. 1 is a perspective view schematically illustrating theconstruction of a conventional field emission display having a diodefield emitter,

[0037]FIG. 2 is a perspective view schematically illustrating theconstruction of a conventional active-matrix field emission displayhaving the diode field emitter,

[0038]FIG. 3 is a perspective view schematically illustrating theconstruction of an active-matrix field emission display having a gateplate according to the present invention,

[0039]FIG. 4 is a perspective view schematically illustrating a cathodeplate, a gate plate and an anode plate in the field emission displayaccording to the present invention,

[0040]FIG. 5 is a cross-sectional view illustrating a pixel structure ofthe field emission display according to one embodiment of the presentinvention,

[0041]FIG. 6 is a cross-sectional view illustrating the pixel structureof the field emission display according to another embodiment of thepresent invention,

[0042]FIG. 7 is a cross-sectional view illustrating the pixel structureof the field emission display according to still another embodiment ofthe present invention, and

[0043]FIG. 8 is a cross-sectional view illustrating the pixel structureof the field emission display according to further still anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0044] A field emission display of the present invention issignificantly different comparing with that of the prior art field, in acathode plate and the structure of a gate plate and a method of drivingthe same. Hereinafter, the field emission display according to thepresent invention will be described in detail with reference to FIG. 3to FIG. 8.

[0045]FIG. 3 is a perspective view schematically illustrating aconstruction of an active-matrix field emission display having a gateplate according to the present invention and FIG. 4 is a perspectiveview schematically illustrating a cathode plate, a gate plate and ananode plate in a field emission display according to the presentinvention. The field emission display includes the cathode plate 100,the gate plate 200 and the anode plate 300.

[0046] As shown in FIG. 4, the cathode plate 100 includes a belt shapedrow signal line 120S and column signal line 120D on an insulatingsubstrate 110 including glass, plastic, various ceramics, and the like,wherein the belt shaped row signal line and column signal line are madeof a metal and enable to a row/column addressing. The unit pixels aredefined by the row signal lines 120S and the column signal lines 120D.Each pixel includes a film-shaped (thin film or thick film) fieldemitter 130 made of diamond, diamond like carbon, carbon nanotube, etc.and a control device 140 of the field emitter. It is preferred that thecontrol device 140 includes two terminals connected to at least the rowsignal line 120S and the column signal line 120D and one terminalconnected to the film-shaped field emitter 130. For example, the controldevice 140 may be an amorphous thin film transistor, a polysilicon thinfilm transistor, a metal-oxide-semiconductor field effect transistor, orthe like.

[0047] The gate plate 200 includes gate holes 220 penetrating asubstrate 210, and a gate electrode 230 made of a metal around the gateholes 220. The substrate 210 of the gate plate 200 can be formed by atransparent substrate such as glass, plastic, various ceramics, varioustransparent insulating substrates, or the like, and if necessary, anon-transparent substrate can be used as the substrate. The thickness ofthe gate plate 200 may be for example 0.01 to 1.1 mm and the thicknessof the gate electrode may be several hundreds of Å to several thousandsof Å. The metal used for the gate electrode 230 may be chrome, aluminum,molybdenum, and the like, but not limited thereto. In addition, the gateholes 220 can be formed to be opened a little bit larger than each pixelso that the holes 220 can serve as the aperture of the unit pixel (forexample, several tens of μm to several hundreds of μm) formed in thecathode plate 100. Those skilled in the art will appreciate that thesize of the gate hole 220, the shape of the section, the thickness ofthe gate plate 200, the thickness of the gate electrode 230, the shapeand distance separated from the field emitter 130, etc. are notspecially limited but can be variously modified.

[0048] The anode plate 300 includes a transparent electrode 320, andphosphors 330 of red (R), green (G) and blue (B) formed on a portion ofthe transparent electrode 320, on a transparent insulating substrate 310made of glass, plastic, various ceramics, etc., as shown in FIG. 4.

[0049] Meanwhile, in the cathode plate 100, the gate plate 200 and theanode plate 300, the field emitter 130 of the cathode plate 100 arevacuum packaged parallel to the phosphor 330 of the anode plate 300through the gate holes 220 of the gate plate 200, while facing eachother, by means of using spacers 400 as a supporter, as shown in FIG. 3and FIG. 4. The spacers 400 can be manufactured by glass beads,ceramics, polymer, etc. and may have a height in the range ofapproximately 200 μm to 3 mm.

[0050] On the other hand, the gate electrode 230 may be also used as anoptical-shielding film by selecting the type of a metal used as the gateelectrode 230 or the thickness of the film.

[0051] Next, the method of fabricating the field emission displayaccording to one embodiment of the present invention will be describedin detail with reference to FIG. 5. FIG. 5 is a cross-sectional viewillustrating the unit pixel of the field emission display according tothe present invention.

[0052] In an embodiment of FIG. 5, the gate plate is adhered to thecathode plate, while the anode plate is separated and vacuum packagedfrom the gate plate by the spacer supported between the anode plate andthe gate plate. The cathode plate, the gate plate and the anode platecan be fabricated separately and then combined together.

[0053] The unit pixel of the field emission display shown in FIG. 5includes the cathode plate, the gate plate and the anode plate. Thecathode plate has the substrate 110, the thin film transistor element,the field emitter, etc.

[0054] The thin film transistor element includes a gate 141 made of ametal on the substrate 110, a gate insulating film of the thin filmtransistor 142 composed of an amorphous silicon nitride (a-SiNx) film ora silicon oxide film on the substrate 110 including the gate 141, anactive layer of the thin film transistor 143 formed of amorphous silicon(a-Si) on a portion of the gate 141 and the gate insulating film 142, asource 144 and a drain 145 of the thin film transistor formed of n-typeamorphous silicon at both ends of the active layer 143, a sourceelectrode 146 of the thin film transistor formed of a metal on a portionof the source 144 and the gate insulating film 142, a drain electrode147 of the thin film transistor formed of a metal on a portion of thedrain 145 and the gate insulating film 142, a source electrode 146 ofthe thin film transistor, and an interlayer insulating film (passivationinsulating film) 148 composed of the amorphous silicon nitride film orthe silicon oxide film on the active layer 143 of the thin filmtransistor and a portion of the source electrode 146 and the drainelectrode 147. Meanwhile, an electron-convergence electrode 149 formedof a metal may be intervened on a portion of the interlayer insulatingfilm 148. The electron-convergence electrode 149 can serve as anoptical-shielding film and perform the function of focusing theelectrons emitted from the field emitter 130, by applying for a propervoltage. The field emitter 130 may be formed of diamond, diamond likecarbon, carbon nanotube, and the like on a portion of the drainelectrode 147 of the thin film transistor.

[0055] The surface of the gate plate having no gate electrode 230 isadhered to the cathode plate. At this time, said gate plate are arrangedin accordance with the field emitter 130 of the cathode plate, the anodeplate are separated from the gate plate by using the spacers 400 as thesupporter between them. Further, said anode plate is arranged and vacuumpackaged against the phosphor 330 of the anode plate and the fieldemitter 130 of the cathode plate. The spacers 400 serve to keepisolation between the cathode plate/the gate plate and the anode plate.It is not necessarily to be installed in every pixel.

[0056] The gate plate includes the gate holes 220 formed by penetratingthe glass substrate 210 and the gate electrode 230 made of a metalaround the gate holes 220.

[0057] The anode plate includes the transparent electrode 320 formed ona portion of the substrate 310, phosphors 330 of red, green and blueformed on a portion of the transparent electrode 320, and a black matrix340 formed between said phosphors 330.

[0058] On the other hand, since the gate plate and the cathode plate canbe fabricated separately, the manufacturing process can be readilyperformed and the gate insulating film in the field emitterfundamentally can be removed. Therefore, the separately fabricated gateplate, the cathode plate and the anode plate are combined together. As aresult, it is possible to significantly improve the manufacturingproductivity and yield of the field emission display.

[0059] Hereinafter, driving principle of the field emission displayaccording to the present invention will be described with reference toFIG. 3 to FIG. 5.

[0060] A DC voltage of 50 to 1500V is applied to the gate electrode 230of the gate plate to induce an electron emission from a film-shapedfield emitter 130 of the cathode plate. At the same time, said emittedelectrons are accelerated with high energy by applying a high voltage ofabove 2 kV to the transparent electrode 320 of the anode plate.Meanwhile, an operation of a control device of the field emitter in eachpixel of the cathode plate can be controlled, by adjusting the voltagesapplied to the row signal line 120S and the column signal line 120D ofthe display. In other words, the control device 140 of the field emitterin each pixel represents an image by controlling an electron emission ofthe field emitter 130.

[0061] At this time, the voltage applied to the gate electrode 230 ofthe gate plate serves to prohibit electron emission of the field emitterby the anode voltage, and also prevent local arching by forming arelatively uniform potential between the anode plate and the gate plate.The voltage applied to the row signal line 120S and the column signalline 120D of the display is applied to the gate and the source of thethin film transistor. The voltage applied to the gate of thin filmtransistor may be over 5V to below 50V when the thin film transistorhaving the active layer formed of amorphous silicon is turned on andbelow 5V or a negative voltage when the transistor is turned off.Further, the voltage applied to the source may be approximately in therange of 0 to 50 V. The control of the applied voltage, as describedabove, can be made by an external driver circuit (not shown).

[0062] Subsequently, gray scale representation of the field emissiondisplay will be described.

[0063] Gray scale representation of the common field emission display isimplemented using a pulse width modulation (PWM) mode. This is the modethat the duration of the voltage of the data signal applied to the fieldemitter is controlled to represent gray scale. Wherein, gray scale isrepresented by the difference in the amount of the electrons emitted fora given time. In other words, if there are plenty of the amounts in theelectrons for a given time, a corresponding pixel emits a light havinghigh brightness. However, the mode has a critical limitation where thewidth (time) of the pulse assigned to the unit pixel is graduallyreduced in implementing a large-scale, high-resolution screen. Further,it has a problem that it is difficult to exactly control the amount ofemitted electrons.

[0064] The driving method according to the present embodiment canovercome the above problems. Gray scale representation of the fieldemission display may use the pulse width modulation (PWM) mode or thepulse amplitude (PAM) mode separately, or a combination of them. The PAMmode is that gray scale is represented based on the difference of theamplitude applied as the data signal. This mode employs that the amountof the electrons transported to the field emitter may be varied by thedifference in the level of the voltage applied to the source in a statewhere the thin film transistor is turned on. Gray scale can berepresented by differentiating the level into two or more levels. Thisdriving method can be applied to implement the large-scale screen andcontrol electrons emission constantly.

[0065] Meanwhile, a constant voltage may be applied to theelectron-convergence electrode 149 in order to help the electronsemitted from the field emitter 130 of the cathode plate to be wellconverged on the phosphor 330 of the anode plate, and also, to prohibitfield emission of the field emitter 130 by the anode voltage along withthe gate electrode 230 of the gate plate. In case of using theelectron-convergence electrode 149 as the optical-shielding film, it ispossible to prevent the active layer of the thin film transistor 143from being exposed to the phosphor of the anode plate or surroundinglights.

[0066] Now, other embodiments or modifications of the present inventionwill be described in detail with reference to FIG. 6 to FIG. 8.

[0067]FIG. 6 is a cross-sectional view illustrating a pixel structure ofa field emission display according to another embodiment of the presentinvention.

[0068] The structures of a cathode plate, a gate plate and an anodeplate in FIG. 6 are the same as those of FIG. 5, except that the portioninto which spacers 400 are inserted is between the gate plate and thecathode plate. In other words, the surface of the gate plate not havinga gate electrode 230 is adhered to the anode plate.

[0069]FIG. 7 is a cross-sectional view illustrating a pixel structure ofa field emission display according to still another embodiment of thepresent invention.

[0070] The structure of the anode plate in FIG. 7 is the same as that ofFIG. 5, except that the field emitter 130 of the cathode plate has aplurality of dots and there are many the gate holes 220 of the gateplate so that they are coincident with the number of the dots of thefield emitter 130 in the cathode plate. Such a structure has aneffective advantage in applying a high voltage to the electrode of theanode plate. In addition, it can prevent the anode electric field fromexerting a harmful influence on the field emitter through the pluralityof the dots.

[0071]FIG. 8 is a cross-sectional view illustrating a pixel structure ofa field emission display according to further another embodiment of thepresent invention.

[0072] The structures of a cathode plate and a anode plate in FIG. 8 arethe same as those in FIG. 7, except that gate holes 220 of the gateplate has a dual hole including a larger hole than the phosphor 340 ofthe anode plate and a small hole corresponding to the field emitter 130of the cathode plate, the surface of the gate plate having no gateelectrode 230 is adhered to the anode plate, and the cathode plate isformed by vacuum packaging in a state where the cathode plate and thegate plate are separated with the spacers supported between them.

[0073] The forgoing embodiments are merely exemplary and are not to beconstrued as limiting the present invention. The present teachings canbe readily applied to other types of apparatuses. The description of thepresent invention is intended to be illustrative, and not to limit thescope of the claims. Many alternatives, modifications, and variationswill be apparent to those skilled in the art.

[0074] As described above, according to the present invention, a fieldemission display includes an anode plate consisting of a glasssubstrate, a cathode plate and a gate plate. The cathode plate includessignal lines for which row/column addressing is possible and pixels eachdefined by the row/column signal lines, wherein each pixel has afilm-shaped field emitter and a control device of the field emitter.Further, the row/column driving voltage of the display can be reducedsignificantly by inputting and driving scan and data signals of thedisplay to the control device of each pixel. Therefore, a cheaplow-voltage driving circuit can be used instead of a high-voltagedriving circuit that is required for row/column driving of theconventional field emission display.

[0075] Meanwhile, according to the present invention, since the electricfield for field emission can be applied through the gate electrode ofthe gate plate, the distance between the anode plate and the cathodeplate can be freely controlled, thereby a high voltage can be applied tothe anode. Therefore, the present invention has an advantageous effectthat it can significantly increase the brightness of the field emissiondisplay. Further, the voltage applied to the gate electrode of the gateplate serves to prohibit electron emission of the field emitter by theanode voltage, and also prevent local arching by forming a relativelyuniform potential between the anode plate and the gate plate. Thus thelife of the field emission display can be improved significantly.

[0076] In addition, since the gate plate and the cathode plate can befabricated separately and then assembled together, manufacturing processcan be readily performed and a breakdown of a gate insulating film inthe field emitter can be removed fundamentally. Thus, the presentinvention can be provided to improve the manufacturing productivity andyield of the field emission display significantly.

[0077] While the present invention has been described with reference tothe particular illustrative embodiments, it is not to be restricted bythe embodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

What is claimed is:
 1. A field emission display having a gate plate,comprising: an anode plate having a transparent electrode on a substrateand a phosphor on a portion of the transparent electrode; a cathodeplate having row/column signal lines of a belt shape for whichrow/column addressing is possible on the substrate, and pixels eachdefined by the row signal line and the column signal line, wherein eachpixel has a film-shape field emitter and a control device forcontrolling the field emitter, having two terminals connected to atleast the row/column signal lines and one terminal connected to thefilm-shape field emitter; a gate plate, wherein each pixel has at leastone of gate hole penetrating therein and a gate electrode around the topof the gate hole; and spacers for supporting the gate plate between thecathode plate and the anode plate, wherein the field emitter of thecathode plate is constructed to be opposite to the phosphor of the anodeplate through the gate holes and is formed by vacuum packaging.
 2. Thefield emission display as claimed in claim 1, wherein the anode plate,the cathode plate and the gate plate are formed of different insulatingsubstrates.
 3. The field emission display as claimed in claim 1, whereinthe spacers are formed between the cathode plate and the gate plate. 4.The field emission display as claimed in claim 1, wherein the spacersare formed between the anode plate and the gate plate.
 5. The fieldemission display as claimed in claim 1, wherein the phosphor of eachpixel is the phosphor of red (R), green (G), or blue (B).
 6. The fieldemission display as claimed in claim 1, further comprising a blackmatrix at a given region between the phosphors of the anode.
 7. Thefield emission display as claimed in claim 1, wherein the field emitteris composed of a thin film or a thick film comprising a diamond, adiamond carbon, or a carbon nanotube.
 8. The field emission display asclaimed in claim 1, wherein the control device is a thin film transistoror a metal-oxide-semiconductor field effect transistor.
 9. The fieldemission display as claimed in claim 1, wherein the gate electrode isapplied to a DC voltage to induce an electron emission from thefilm-shaped field emitter in the cathode plate; the emitted electrons isaccelerated with high energy by applying the DC voltage to thetransparent electrode of the anode plate; and scan and data signals areaddressed to the control device of the field emitter in each pixel ofthe cathode plate, whereby the control device of the field emittercontrols the electron emission of the field emitter to represent images.10. The field emission display as claimed in claim 9, wherein the gateelectrode of the gate plate is applied to the DC voltage in the range of50 to 1500V and the transparent electrode of the anode plate is appliedto the DC voltage of over 2 kV.
 11. The field emission display asclaimed in claim 9, wherein the image is represented by gray scale, bychanging the pulse amplitude and/or pulse width (duration) of the datasignal voltage applied to the field emitter through controlling of thecontrol device.
 12. The field emission display as claimed in claim 11,wherein the voltage of the data signal applied to the field emitter isthe pulse in the range of 0 to 50V.
 13. The field emission display asclaimed in claim 1, further comprising an electron-convergence electrodebetween the cathode plate and the gate plate.
 14. The field emissiondisplay as claimed in claim 13, wherein the electron-convergenceelectrode helps the electrons emitted from the field emitter to be wellconverged on the phosphor of the anode plate and, further to prohibitthe electron emission of the field emitter by the anode voltage alongwith said gate electrode of the gate plate, by applying the constantvoltage to said electron-convergence electrode.
 15. The field emissiondisplay as claimed in claim 13, wherein the electron-convergenceelectrode is intended to serve as an optical-shielding film.
 16. Thefield emission display as claimed in claim 1, wherein the field emitterincludes dots divided into a plurality of regions and the gate hole ofthe gate plate has the number corresponding to each of the dots.
 17. Thefield emission display as claimed in claim 1, wherein the control deviceis a thin film transistor, which comprises; a gate made of a metal onthe cathode plate; a gate insulating film formed on the cathode plateincluding the gate; an active layer made of a semiconductor thin film ona portion of the gate and the gate insulating film; a source and a drainformed at both ends of the active layer; and an interlayer insulatinglayer having a contact hole for connecting the source and the drain tothe electrode.
 18. The field emission display as claimed in claim 17,further comprising an electron-convergence electrode made of a metal onthe interlayer-insulating layer.
 19. The field emission display asclaimed in claim 17, wherein the active layer of the thin filmtransistor consists of amorphous silicon or polysilicon layer.
 20. Thefield emission display as claimed in claim 17, wherein the interlayerinsulating film consists of an amorphous silicon nitride film or asilicon oxide film.